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bimmaster, BMW Technician
Category: BMW
Satisfied Customers: 1882
Experience:  3 years dealer experience, master bmw tech
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2000 BMW 528i: P1188 and P1189 engine codes

Resolved Question:

What problems would trigger P1188 and P1189 engine codes. The 2000 BMW 528i car seems to be running fine.
Submitted: 6 years ago.
Category: BMW
Expert:  bimmaster replied 6 years ago.
Hi, welcome to just answer.
Those faults indicate a problem with the air/fuel mixture as detected by the pre-cat o2 sensors.
The normal cause for these faults is a vacuum leak. Here are the common places for leaks:
The rubber intake tubes between the air mass sensor and throttle. The rubber cracks and splits, allowing un metered air to enter the engine.

The crankcase vent valve (ccv) mounted under the intake can fail and cause these faults and a rough idle. Try removing the oil cap with the engine running to see if there is a strong vacuum holding the cap down, or if the engine idle speed changes. These would indicate the ccv is bad.

Sometimes aftermarket performance intake systems can cause these faults. Make sure you have the stock style paper air filter.
Customer: replied 6 years ago.

I just purchased this car yesterday from a used car dealership. I need to know what to ask the dealership to check or just walk away from the deal. Is this a major problem or a minor problem? The autozone employee who pulled the codes said it might possibly be the massflow sensor or the o2 sensors.



Expert:  bimmaster replied 6 years ago.
It's normally not a majorly expensive cost, but there are many common causes for these faults. Have them check the items I mentioned above. Or if they are not familiar with bmws, have them pay for a diagnostic at the bmw dealer service department.

The rubber intake tube is the most common.
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